Berlin  - While Usain Bolt and Tyson Gay are finally set to meet in a major event 100 metres final at the world championships on Sunday, other events see a long list of absentees.

Marathon world record holder Haile Gebrselassie, Olympic decathlon champion Bryan Clay, Chinese hurdler Liu Xiang and German marathon hope Irina Mikitenko are just some of those not in Berlin for the big event August 15-23.

The 100m showdown between Bolt and Gay comes one year after Gay limped out in the Olympic semi-finals and is the biggest race for them of the year.

Marathon runner, by contrast, have other priorities.

Gebrselassie has decided to run the regular Berlin Marathon in September, where he set world records in 2007 and 2008, rather than compete at the worlds over the 42.195-kilometres distance.

Olympic champion Sammy Wanjiru has chosen to go for the Ethiopian's record in the Chicago Marathon on October 11.

"My plan for the fall is to lower my personal record, and the Chicago Marathon course is the best opportunity for me to achieve that," Wanjiru said of a circuit that has seen five world records.

The men's 110m hurdles are without the last two world champions.

The 2007 winner Liu continues rehabilitating his injured Achilles tendon which forced him to withdraw from the Beijing Games, and the 2005 winner Ladji Doucoure of France is also out injured.

"The current recovery training is very important to Liu and we don't want it to be interrupted by the trip to Berlin. So, it's better for him to watch the event on TV at home," said Feng Shuyong, vice-director of the Chinese Athletics Administrative Centre (CAAC).

Injury casualties also include 2008 Olympic champions Andrey Silnov of Russia (high jump) and American Bryan Clay (decathlon), and German decathlon medal hope Paul Schrader is also sidelined.

"My great dream of competing in the Berlin Olympic stadium in front of a home crowd has been shattered," said the 22-year-old decathlete.

An even bigger blow for the host nation was the withdrawal of marathon gold medal contender Mikitenko. The fastest woman in the world this year and two-time London winner said she was unable to run in the wake of her father's death in late July.

Reigning three-time world heptathlon champion Carolina Kluft, who now competes in long jump, is out with a hamstring injury and fellow- Swede Susanna Kallur will not be in the 100m hurdles owing to injury.

British heptathlete Kelly Sotherton, a bronze medalist at the 2004 Athens Olympics and in Osaka two years ago, is out due to a heel injury while New Zealand 1,500m Olympic silver medallist Nick Willis has not recovered in time from hip surgery.

Meanwhile, Olympic 1,500m champion Rashid Ramzi has been forced to miss the worlds because of doping at the Beijing Games, one of several athletes caught using the blood booster CERA in retests of the Olympic samples.

Four Jamaican runners, including 100m medal contender and Bolt's training group member Yohan Blake, may also miss out in Berlin, with their fate to be decided early in the week. (dpa)